Accumulator for vehicle suspension



P- H. TAYLOR ACCUMULATOR FOR VEHICLE SUSPENSION Original Filed May 16,1957 Dec. 24, 1963 4 Sheets-Sheet 1 IN V EN TOR. EUZHT GJZ ,aww M Qz ZornyS Dec. 24, 1963 P. H. TAYLOR ACCUMULATOR FOR VEHICLE SUSPENSION 4Sheets-Sheet 2 INVENTOR. Ru! )1? 2 a 3 Z 07' BY 1 fi m fl mqn M 0250721655.

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O A coMPRF-SS\B'L'TY Pauz H. Tqyz r' United States Patent 3,115,003ACCUMULATOR FOR VEHICLE SUSPENSION Paul H. Taylor, Grand Island, N.Y.,assignor to Tayco Development, Inc., North Tonawanda, N.Y., acorporation of New York Original application May 16, 1957, Ser. No.659,629, now Patent No. 2,949,315, dated Aug. 16, 1960. Divided and thisapplication Aug. 16, 1960, Ser. No. 49,917

2 Claims. (Cl. 60-23) This invention relates -to vehicle suspensionsystems utilizing energy storage and dissipation means. Moreparticularly, the invention relates to a liquid spring ve hiclesuspension system which is adapted to resiliently support and controlthe ride of the vehicle and to accomplish vehicle leveling.

The present application is a division of my earlier copendingapplication Serial No. 659,629 filed May 16, 11957, now Patent No.2,949,315 issued August 16, 1960, and entitled Compressible LiquidVehicle Suspension and Power System. This divisional case covers thecompressible liquid accumulator and control apparatus portion of theinvention which was divided from the parent application pursuant to afinal requirement for restriction made by the Patent Oflice.

In vehicles of all types the modern trend has been to provide means forraising and lowering the vehicle so as to maintain at some predeterminedposition or vehicle level, a soft, long stroke, cushioned ride, whateverthe loading of the vehicle may be. The aim is to maintain thepredetermined level while still providing long stroke cushioning toreduce impact loading on the passen-gers, vehicle structure and cargo.Long stroke cushioning is particularly desirable in connection with thehuman body, the natural frequency of which has been roughly placed atbet-ween sixty and ninety strokes per minute. If at all possible thisfrequency range should not be exceeded.

Present vehicles, particularly of the heavier type, are usuallysuspended on mechanical springs, which, in order to accommodate overloadand impact stresses, are of the heavy, leaf variety providing a short,stifi bottoming ride when fully loaded. In some heavy trucks, forexample, less than inch of travel is provided with the vehicles fullyloaded. The resulting impact, from bumps and the like in the road, isextremely detrimental to the vehicle, the operator, the cargo and theroads.

Because of the poor riding qualities of heavy trucks and largeolT-the-road vehicles there is a high incidence of kidney ailments amongoperators, resulting in fatigue induced accidents and shortening of theworking life of the operators. The damage to cargo in transit directlyattributable to such poor riding qualities is impossible to accuratelycalculate but obviously runs into many millions of dollars annually. Asa result of the extremely detrimental elfect of high impact loading onroads, many states have placed limits on cargo weights, thus seriouslyhampering the motor cargo industry and necessitating unusually hightruck freight rates due to excessive costs. Furthermore, since heavyvehicles require extremely stilt springs to accommodate the fully loadedcondition, the empty ride of such vehicles many times offers morepunishment to the driver than the full ride. Present suspensionsordinarily have an excessive unsprung mass to accommodate heavy impactloading and this presents another difficulty in that it seriouslyaffects the cargo carrying capacity of the vehicle.

The problem of vehicle leveling is becoming increasingly important. Ifthe riding level of the vehicle can be maintained constant whatever theloading condition may be, then the problem of providing a long stroke,

3,115,003 Patented Dec. 24, 1963 properly cushioned ride under allconditions is very much simplified. Furthermore, the maintenance of asubstantially constant vehicle level makes for easier and safer drivingand adds greatly to the comfort of the operator and passengers.

In short, then, it is highly desirable to provide a vehicle suspensionsystem which will achieve a long stroke, properly cushioned ride underall loads and will accomplish vehicle leveling for all load conditions.At the same time it is desirable to provide lighter vehicle supportingstructures which in turn will reduce unsprung impact forces and willpermit larger pay loads.

It is accordingly an important object of the present invention toprovide an improved vehicle suspension system.

Another object of the invention is to provide a vehicle suspensionsystem which will provide a long stroke cushioned vehicle ride under allload conditions.

A further object of the invention is to provide a vehicle suspensionsystem accommodating improved means for accomplishing vehicle levelingunder all loading conditions.

A still further object of the invention is to provide a vehiclesuspension system capable of achieving a cushioned ride under allloading conditions and incorporating means for accomplishing vehicleleveling under all con ditions.

An important object of the invention is to provide a vehicle suspensionsystem incorporating vehicle leveling means utilizing waste thermalenergy of the vehicle engine.

Another object of the invention is to provide a vehicle suspensionsystem capable of accomplishing vehicle leveling without the necessityof incorporating hydraulic pumps or the like.

A further object of the invention is to provide a vehicle suspensionsystem incorporating vehicle leveling means capable of utilizing outsideheat sources in the event of low ambient temperatures.

An additional object of the invention is to provide a vehicle suspensionsystem embodying improved dampening means.

Another object of the invention is to provide an improved auxiliarysuspension system for supplementing existing mechanical systems:

A specific object of the invention covered in this divisionalapplication is to provide improved accumulator and control apparatus forincorporation in a vehicle suspension system to accomplish the aboveobjects.

An overall object of the divisional invention is to pro vide improvedaccumulator and control apparatus.

Other objects, features and advantages will be apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIGURE 1 is a schematic plan view of a vehicle sus pension systemaccording to the present invention.

FIGURE 2 is a schematic sectional view of the accumulator and controlportion of a suspension system such as shown in FIGURE 1.

FIGURE 3 is a schematic sectional view of another embodiment of anaccumulator and control arrangement.

FIGURE 4 is a schematic sectional view of a third embodiment of anaccumulator and control arrangement.

FIGURE 5 is an enlarged sectional view of a prerterred accumulator andrelated elements for incorporation in the system of FIGURE 1.

FIGURE 6 is an enlarged sectional view of a wheel strut or cylinder foruse in the suspension system of FIGURE 1. i l

FIGURE 7 is a graphic representation of the opera- 'J tion of a typicalvehicle suspension system according to the present invention- In FIGURE1 is illustrated a vehicle suspension system generally designated by thereference numeral 20 for supporting a vehicle superstructure (not shown)incorporating an internal combustion engine 22, a power transmission 24,a drive shaft 26, a differential 28, rear wheel drive axles 30, 30, reardriving wheels 32, 32, and front steerable Wheels 34, 34. The vehiclewheels 32 and 34 are rotatably connected in any suitable manner torespective pairs of A frame members 36 and 38, and the A frame membersare pivotally connected to the vehicle frame (not shown) in any suitablemanner for pivoting on axes 40 and 42, respectively. The weight of thevehicle is transferred to the A frame members 36 and 38 through rearwheel cylinders or struts 44, 44 and front wheel cylinders or struts 46,46. The wheel cylinders are of the liquid spring type and will bediscussed in detail later.

The cylinders 44 and 46 on one side are hydraulically connected to anaccumulator 48, and on the other side to an accumulator 50, throughrespective hydraulic conduits or pipes 52, 54, 56 and 58. Theaccumulators will be described in detail later, but for the presentpurpose it suffices to note that they are intended to be filled with acompressible liquid preferably capable of undergoing reversiblepolymorphic transition, or change of non-gaseous form resulting in achange of volume at substantially constant pressure, at temperatures andpressures Within the ranges to be encountered in operation of thevehicle suspension system of this invention. For example, compressibleliquids of the dimethyl siloxane family may be conventionally utilized.

The wheel cylinders 44 and 46 and the lines 52, 54, 56, and 58 areintended to be completely filled with a compressible liquid which willnot undergo polymorphic transition in the temperature and pressureranges to be encountered. For example, non-polymorphic dimethylsiloxanes, conventional hydraulic fluids, or the like can be utilizedfor this purpose. As will be described, the accumulators are constructedso that the two liquids will not mix, although pressure is freelytransmitted between the liquids.

It should be understood that since the wheel units, the accumulators andthe lines are completely filled with liquids, the spring effect isachieved mainly through actual compression of the liquids themselves,but elastic deflection of the walls of the various vessels and tubes isutilized to some extent.

For supplying heat to the accumulators 48 and 50 to change the volume orthe pressure level of polymorphic transition of the liquids therein, theaccumulators are connected through respective control valves 60 and 62to the opposite sides 64 and 66 of the engine exhaust system. The valves60 and 62 may be controlled in any suitable manner such as by connectingthe valves to vehicle level sensing means to be described in detaillater.

To provide an initial reference position for maintaining the samevehicle height at the front and rear, coil centering springs 68, 68surround the rear wheel cylinders 44 and are resiliently disposedbetween the A frames 36 and the vehicle frame (not shown). The coilsprings 68 do not provide primary support for the vehicle but correctthe tendency of the vehicle to nose up or down due to uneven fore andaft loads, such as encountered during acceleration or deceleration. Forexample, if the vehicle is braked so that it tends to nose down, thesprings 68 prevent or hinder the draining of the front wheel cylindersand the overfilling of the rear wheel cylinders since the coil springsresiliently urge the frame toward a static fore and aft level. Ifdesired, torsion bars could be used at pivot points 40 to stiffen thespring rate on the rear suspensions.

For replenishing the hydraulic fiuid in the lines and in the wheelcylinders and for providing an emergency source of hydraulic power anauxiliary pump 70 may be incorporated. The pump 70 may be of anysuitable type and is driven by the vehicle engine 22 for feedinghydraulic fluid under pressure from a suitable sump (not shown) intoauxiliary lines 72 and 74 Which are connected, respectively, to thelines 52 and 56. A valve 76 of any suitable construction is provided atthe juncture between the pump outlet and the lines 72 and 74. The valveis normally closed to prevent communication between the lines 72 and 74,but when the pump 70 is to be operated the valve is opened.

To provide additional resiliency in the suspension system the lines 52,54, 56 and 58 may be formed of a resilient material such as nylon orberyllium copper.

In the system schematically illustrated in FIGURE 1 approximately 10% ofthe total compressible liquid is carried by the lines, approximately 20%is carried by the wheel units, and approximately 70% is carried by theaccumulators. Of course, these proportions can be varied to suit.

The suspension system of FIGURE 1 resiliently supports the vehicle onthe road wheels through the wheel cylinders as a result of the combinedresiliency of the compressible liquid in the cylinders themselves, inthe lines and in the accumulators, and through the resilient eiTect ofthe lines themselves if they are constructed of suitable material. Thevehicle can be raised or lowered at will, or a constant level can bemaintained regardless of the load in the vehicle by varying the heatapplied to the accumulators. If the accumulators are heated, the liquidtherein will expand and raise the vehicle, and, conversely, if theaccumulators are cooled the liquid will contract and lower the vehicle.

Since a polymorphic liquid is preferably utilized in the accumulators,variation of the temperature will vary the pressure at which the liquidwill undergo polymorphic transition. By varying the temperature tomaintain the polymorphic transition pressure substantially equal to thepressure in the accumulators, the liquid volume will be maintainedsubstantially constant and the vehicle will be resiliently supported inthe polymorphic range of the liquid for obtaining the effect of internalfluid dampening of road shock, to be discussed in detail later.

If the control valves and 62 are connected to and controlled by vehiclelevel sensing means, the amount of exhaust heat supplied to theaccumulators can be increased or decreased automatically to raise orlower the vehicle as required. If desired, the liquid in the suspensionsystem can be connected to hydraulically actuate accessories of any typesuch as power steering, power brakes, power windows, power scoops, powerbuckets, power pile drivers, power starters, or the like, and the fluidbled off for such purposes can be compensated for by increasing the heatsupplied to the accumulators, thus reducing the need for accessory pumpsor other sources of power.

It is important to note that the only source of power utilized is thewaste heat of the engine from the exhaust and this heat isadvantageously utilized for vehicle leveling and for supplying surge oremergency accessory power.

FIGURE 2 illustrates an accumulator and control system which can beutilized in the vehicle suspension system of FIGURE 1. The schematicallyillustrated accumulator of this figure is designated by the referencenumeral 80. The accumulator includes an insulated outer casing 82 havinga container 84 supported therein. The container 84 is preferablymetallic and is constructed with a plurality of fins 86 for conductingheat.

The container 84 is filled with a compressible accumulator liquidcapable of undergoing a reversible polymorphic transition within therange of pressures and temperatures to be encountered in operation ofthe system. For example, the liquid might be one of the class ofdimethyl 'siloxane liquids, commonly referred to as silicones, orbenzene.

The characteristics of one such polymorphic liquid are illustrated inFIGURE 7 which is a plot of pressure (in pounds per square inch) versusvolume reduction (in percent). The particular liquid illustratedmaintains a given low volume polymorphic form at 6 5 Fahrenheitregardless of pressure, as illustrated by the dash line marked A and thesolid line continuation marked B. At 75 Fahrenheit this same liquid iscapable of undergoing a reversible polymorphic transition from one formto another at a constant pressure of 4,000 p.s.i., so that below thispressure the liquid assumes a high volume form illustrated by the solidline C and above this pressure assumes the low volume form asillustrated by the solid line B. The polymorphic transition at 75 F.between the high volume form of line C and the low volume form of line Bis illustrated by the connecting line D. At 80 F. the liquid is capableof undergoing constant pressure polymorphic transition or change in format approximately 6300 psi. as illustrated by the dash line marked E. At90 F. the same liquid undergoes polymorphic transition at approximately8300' psi. as illustrated by the dash line marked F, and at 110 F. theliquid undergoes polymorphic transition at approximately 9800 p.s.i. asillustrated by the dash line marked G. Of course, at intermediatetemperatures intermediate pressurc-vo1ume curves are followed. It willbe understood that all the lines marked D, E, F and G illustratepolymorphic change under perfect isothermal conditions in which all ofthe necessary heat energy is instantly supplied or absorbed duringpolymorphic transition between the low volume form and the high volumeform.

Referring back to FIGURE 2, the container 84 includes a flexible bulb ordiaphragm 38 therein which is completely filled with a non-polymorphiccompressible wheel cylinder liquid and is connected through a passageway'90 and through a valve "92 to wheel cylinder passages 94 and 96. Forexample, the passages 94 and 96 could be connected to front and rearwheel cylinders such as those illustrated in FIGURE l. It will be seenthat the pressure of the wheel cylinder liquid will be transmitted tothe polymorphic accumulator liquid in the container 84, and vice versa,but the accumulator liquid and the Wheel cylinder liquid will not beintermixed because of the presence of the diaphragm 88.

For varying the temperature of the accumulator liquid the casing 82 isconnected to a source of heat, such as engine exhaust gas, by means ofan inlet passage dd, and an exhaust passage 1% is provided to achievecirculation of the heated gas through the casing. The flow of exhaustgas is controlled by a valve 192 which is operated by an electric motor1%. The valve It'll is normally biased toward open position.

The motor 164 is grounded and is also connected by means of a lead 1% toa contact dil of a level sensing device I lil. The level sensing device11% includes a movable switch arm 112 connected by means of a lead 114through an ignition switch 116 to the vehicle battery 118. The batteryis grounded as shown to complete the circuit to the motor 1G4 when theignition switch is closed and the arm 112 and contact 108 are engage Thelevel sensing device may include an arm 120 connected in any suitablemanner (not shown) for sensing the level of the vehicle frame relativeto the wheels so that when the frame is below a certain position, thecontact 168 and the arm 1.12 are disconnected, but when the frame movesupwardly suiliciently, contact is made completing the circuit to themotor 104'. The completion of the circuit causes the motor to beenergized moving the valve 102 toward its closed position to reduce theamount of heated exhaust gas passing through the casing 82 and to reducethe heat applied to the accumulator, so that the accumulator liquidvolume is reduced and the vehicle is lowered until the contact isbroken.

To provide for vehicle leveling at start before the exhaust gas has hadan opportunity to heat the accumulator sufliciently, an electricalresistance unit 122 is provided. The resistance coil 1 22 is groundedand is connected by a lead 124 to a contact 126 of a time delaymechanism 128. The time delay mechanism 128 includes a movable contactarm 130 associated with a solenoid 13 2. The solenoid 132 is groundedand is connected by means of a lead 134 to the switch arm and to acontact 136 in the level sensing device r110. The contact 136 is belowand spaced from the contact 108 in such a position that when the arm 112is moved upwardly sufficiently it engages the contact 1% and when moveddownward sui-ficiently it engages the contact 136.

The valve 92 may be constructed in any suitable manner to freely passpressure surges from the accumulator to the wheel cylinders but todampen reverse pressure surges. For example, the valve may include apair of valve disks 13 8 and 140 having respective restricted centralorifices 14-2 and 144 therethrough. The arrangement is such thatpressure surges within the accumulator will cause the valve disks 138and 149 to open to permit free passage of fluid, but sudden pressuresurges from the wheel cylinders toward the accumulator, occasioned bythe vehicle encountering sudden bumps, will cause the valve disks toclose to cause restricted flow through the orifices. Thus, the valve 92dampens sudden bounce but does not dampen rebound.

The system of FIGURE 2 will maintain a vehicle level as determined bythe sensing device through heat applied to the accumulator and to thepolymorphic liquid therein through the vehicle exhaust system or throughthe electrical resistance 122. The valve 102 is spring biased toward theopen position so that the full effect of exhaust gas is obtained to heatthe polymorphic liquid until sufficient expansion has been obtained toraise the level of the vehicle until the level sensing device closes thecircuit to the contact 108. As long as the contact 108 is closed, thevalve 162 moves toward closed position until the polymorphic liquidbecomes cooled sufficiently to reduce the level of the vehicle to openthe contact.

When the vehicle is started, the polymorphic liquid in the accumulatoris ordinarily cool enough that the con tact .136 of the sensing device110 is engaged. Initially the ignition switch 116 is turned to thestarting circuit. After the vehicle engine has started from the keystart and the switch has returned to its running position, a circuit iscompleted to the time delay solenoid 132, and after a delay period ofseven seconds, the solenoid acts to move the switch arm into engagementwith the contact 126 to complete the circuit to the resistance element122. This causes the polymorphic liquid to be heated very quicklyresulting in a fast increase in volume to raise the vehicle level. Whenthe level has been naised sufiiciently, the sensing switch arm 112 ismoved away from the contact 136 so that the resistance element istie-activated. By this time the vehicle engine is started and the heatof the exhaust gas is utilized for normal control, although if theexhaust gas supply should be cut ofi for some reason the electricalsystem will still maintain the vehicle level.

While as much as 600 watts may be required to initially raise thevehicle by means of the resistance coil 122, only a small fraction ofthis electrical energy is required to maintain the vehicle level afterthe polymorphic liquid is once W'ammed. If desired, the leveling can beaccomplished through the electrical system alone. The system is operatedin this manner if the valve 102 is held closed either purposely orthrough malfunctioning. As long as the circuit is not broken for longerthan seven seconds, the switch 130 will remain closed and control willbe achieved through making and breaking of the contact 136. Ordinaryroad oscillation due to bumps and the like, will not cause the holdingcircuit to be broken.

If the exhaust gas control system is operative, control is ordinarilyachieved through the switch contact 108.

After the circuit through the contact 136 has been broken for sevenseconds, the solenoid 132 is tie-energized and the holding circuit isbroken until the next start.

If the system is utilized in connection with an air conditioned vehicle,the sensitivity of vehicle leveling control can be enhanced by providinga cold air control arrangement in the accumulator similar to that forexhaust gas control. Vv'ith such a system an abnormally high vehiclelevel would not only reduce the flow of exhaust gas but would supply aflow of cooled air to speed the cooling of the polymorphic liquid.-

Whatever means are utilized for heating or cooling the polymorphicliquid in the accumulator, the arrangement is such that the polymorphicliquid temperature will be maintained at substantially the temperatureat which polymorphic transition will occur, depending upon the pressurein the system due to the vehicle weight and its load. Referring again toFIGURE 7, if, for example, the vehicle weight and load are such that thesystem pressure is 4000 p.s.i., for the particular polymorphic liquidillustrated the polymorphic liquid temperature will be maintained atsubstantially 75 F. If the sensing system senses that the vehicle levelis too low, the polymorphic liquid will be heated to raise thepolymorphic level so that the liquid will change or partly change to itslower pressure, higher volume form to raise the vehicle. Vice versa, ifthe vehicle level sensing device senses that the frame is too high, theheat supplied to the polymorphic liquid Will be reduced or cut off sothat the temperature will be reduced, reducing the polymorphic level sothat the liquid will tend to change or partly change to its higherpressure, lower volume form to lower the vehicle. If the vehicle load isincreased so that the pressure is increased, this will be sensed by thelevel sensing device which will raise the temperature and thepolymorphic level according to the requirements of the polymorphicliquid used.

When a polymorphic liquid is utilized in the accumulator, substantialrebound dampening is accomplished within the liquid itself. Referring toFIGURE 7, assume the vehicle is being operated with the system atapproxi mately 6300 pounds pressure and the vehicle encounters a suddenbump. The pressure will he suddenly increased along a line such as theline E since a finite time is required to accomplish polymorphictransition by pressure because of transfer of energy through heat.Polymorphic liquids vary widely as to the time required for polymorphicchange, from a small fraction of a second to several seconds or longer.Because of the time lag the polymorphic change does not follow thetheoretical line E and a considerably higher pressure is encountered. Asthe efliect of the bump is dissipated, the pressure level then follows areverse curve, such as that illustrated by E", which is below the curveE but does not quite coincide with the theoretical isothermal curve E.The area enclosed between the curves E and E represents the energyabsorbed in the polymorphic liquid on rebound, and since the energy isabsorbed in the liquid itself, it is not fed back into the system in theform of rebound energy. Rebound is thus dampened in the liquid itselfrather than by mechanical means. The amount of rebound dampening can bevaried to suit by varying the heat transfer characteristics of theaccumulator 80, such as by changing the arrangement of the fins 86, orby substituting another polymorphic liquid with differentcharacteristics of polymorphic change.

The polymorphic rebound dampening is enhanced by reason of the fact thatthe non-polymorphic liquid in the wheel cylinders and in the linesleading thereto is ordinarily somewhat cooler than the 'liquid in theaccumulator, so that when sudden bounce occurs, a slug of the coolerliquid is suddenly introduced into the flexible diaphragm or bulb in theaccumulator to assist in cooling the accumulator liquid. This results inabsorption of some of the heat, causing polymorphic transition from thehigh volume form to the low volume form, and this additional absorptionof energy further dampens rebound.

The polymorphic dampening varies according to term peraturedifferential. In all conventional shock absorber systems, shockabsorption is greater during winter because of increased viscosityresulting in increased viscous dampening, and in the summer shockabsorption is less because of decreased viscosity. The suspension systemof this invention has the ability to compensate somewhat for thiseffect. In the winter when viscous dampening is greater, the colderliquid from the lines absorbs more energy, thus increasing the energyabsorbed in the polymorphic liquid on rebound and consequentlyincreasing the polymorphic dampening. By the same token, in the summerwhen viscous dampening is less, slugs of liquid introduced into theaccumulator during bounce are not as cold and consequently absorb lessenergy, so that less energy is absorbed in the polymorphic liquid onrebound making the spring rate stiffer. Thus, the system tends toprovide a stable, evenly dampened ride, summer or winter.

An additional advantage of the system of this invention, particularly inconnection with heavy vehicles, is the provision of increasedpolymorphic dampening with increased vehicle load. When the vehicle loadis increased, higher operating temperatures are provided in theaccumulator (to increase the pressure level of polymorphic transition tocompensate for the added pressure in the system due to the added load.For a given ambient temperature the ability of a cold slug of liquidfrom the lines to subtract energy from the hotter accumulator liquiddoes not materially increase. Thus, the cold slug subtracts less of thetotal energy of polymorphic transition, so that less energy is absorbedin the polymorphic liquid on rebound. As a result, at heavily loadedconditions the spring rate is increased at a time when increased springrate is desirable.

Another embodiment of accumulator and control system is illustrated inFIGURE 3. In this embodiment an accumulator is illustrated and includesan outer insulated casing 152 and an inner liquid container 154. Thecontainer 154 is filled with a polymorphic liquid and an electricresistance coil 156 is disposed in the liquid for heating the liquidwhen desired. A flexible diaphragm or bulb 158 is disposed in thecontainer 154 and the bulb is completely filled with a non-polymorphiccompressible liquid and is connected to the front and rear wheelcylinders of one side of a suspension system such as illustrated inFIGURE 1. The casing 152 is provided with an inlet passage 160 and anoutlet passage 162. Thus far the construction and arrangement is quitesimilar to that illus trated and described in connection with FIGURE 2.

For controlling the temperature of the polymorphic liquid contained inthe container 154 a valve 164 is connected to the inlet passage 160 andcontrols flow from a passage 166 and another passage 168. The passage166 is connected to a source of heated fluid, such as hot water comingfrom the engine in the engine cooling system, and the passage 168 isconnected to a source of relatively cool fluid, such as the relativelycool water coming from the radiator of the engine cooling system. Theoutlet 162 is connected back to the vehicle cooling system so that aclosed circuit is provided. An internal control member 170 of the valve164 is connected to an arm 172 which is, in turn, connected to a vehiclelevel sensing arm 174 which senses the height of the vehicle framerelative to the wheels.

When the accumulator control system of FIGURE 3 is utilized in asuspension system, the vehicle level determines the position of therotatable valve member 170. If the vehicle frame is too low, the valvemember is rotated in a counterclockwise direction to increase the flowof hot water from the passage 166, and to decrease the flow ofrelatively cool water from the passage 168. This causes the polymorphicliquid in the container 154 to be heated and the resultant expansionraises the level of the vehicle. Conversely, if the vehicle level is toohigh, the valve member 170 is rotated in a clockwise direction to reduceflow of hot water and to increase flow of relatively cool water toreduce the temperature of the polymorphic liquid and to lower thevehicle level. It is contemplated that any suitable type of dampeningmeans (not shown) can be utilized in connecting the level sensing arm174 to the vehicle in order that the arm be relatively unaffected byordinary road oscillations of the wheels relative to the frame, so thatonly the average level of the frame is sensed and transmitted to thecontrol valve 164. When the vehicle engine and cooling system are coldat start, the vehicle leveling may be accomplished through theelectrical resistance coil 156 which may be connected and controlled inthe manner shown in FIGURE 2.

A third embodiment of accumulator and control system is illustrated inFIGURE 4. In this embodiment an accumulator 180 includes an outerinsulated casing 182 which encloses a finned container 184 containing acompressible polymorphic liquid. A flexible diaphragm or bulb 186 isincluded within the container 184 and is completely filled with acompressible non-polymorphic liquid and connected to the wheel cylindersof one side of a suspension system by means of conduits 188 and 190. Thecasing 182 is provided with an inlet 192 and an outlet 194. Forproviding initial vehicle leveling at start, an electrical resistancecoil 196 is connected through a level sensing switch 198 and an ignitionswitch 200 to the vehicle battery 202. The resistance coil arrangementand operation is substantially the same as shown in connection withFIGURE 2 except that no time delay device is provided although, ifdesired, this feature can be included in exactly the same manner.

For controlling the temperature of the polymorphic liquid in theaccumulator shown in FIGURE 4, a control valve 204 is connected to theinlet 192 and controls flow from a cold air duct 206 and a warm air duct208 through respective valve control members 210 and 212. The cold airduct 206 is connected to the atmosphere and flow may be obtained throughram when the vehicle is moving or by means of a blower (not shown) orboth. The warm air duct is connected to the warm air outlet of thevehicle hot water heater 214 which may be of any suitable construction,such as that shown including a hot water heat exchanger 216 throughwhich heated water from the vehicle cooling system is circulated, sothat the air drawn across the heat exchanger 216 is heated and directedto the warm air duct 208. The valve control members 210 and 212 areoperably connected to a control lever 218, which, in turn, is connectedto and adapted for being rocked by an electric actuating motor 220. Themotor 220 is reversible and its respective reversing contacts areconnected to the upper and lower contacts in the level sensing device198.

The device of FIGURE 4 operates in much the same manner as that ofFIGURE 2 with initial leveling being performed by the resistance coil196 and leveling thereafter being performed through the control valve204 in conjunction with the coil 196. The arrangement is such that whenthe vehicle level is too low, the coil 196 is energized and at the sametime the warm air duct 208 is opened, while the cool air duct 206 isclosed, to heat the polymorphic liquid in the accumulator by warm airfrom the vehicle heater in conjunction with the heating coil and toraise the vehicle level. When the vehicle level gets too high, thereversible motor 220 closes the warm air duct 208, cuts out the coil196, and opens the cool air duct 206 to cool the polymorphic liquid andconsequently to lower the vehicle.

A preferred embodiment of accumulator for use in the schematicallyillustrated systems of FIGURES 1-4 shown in detail in FIGURE 5. Theaccumulator in this figure is generally designated by the referencenumeral 230 and includes an outer insulated casing 232 and an innercontainer 234 disposed in spaced relation in the casing. The

container 234 is provided with a plurality of fins 236 for enhancingheat transfer and is filled with a polymorphic compressible liquid 238.A flexible diaphragm or bulb 240 extends into the container 234 inspaced relation therein and is filled with a non-polymorphiccompressible liquid. The bulb 240 is connected by means of a pair ofconduits 242 and 244 to the front and rear wheel cylinders of one sideof a suspension system such as shown in FIGURE 1. The flow between thewheel cylinders and the bulb 240 is controlled by a dampening valve 246.An electrical resistance heating coil 248 is immersed in the polymorphicliquid 238 and surrounds the bulb 240. The coil is connected to thevehicle battery (not shown) through electrical circuit means 250. Theouter casing 232 is provided with an inlet port 252 and an outlet port254, the inlet port being connected to a source of heated fluid, such asthe vehicle exhaust system, the vehicle cooling system, or the vehicleheater, in the manner shown and described in connection with FIGURES2-4.

The dampening valve 246 includes a valve disk 256 having a centralrestricted orifice 258 therethrough. The disk rests on a plurality offingers 260 which provide for free fluid communication between a passage262 leading directly into the bulb 240 and a chamber 264 containing thevalve disk 256. The arrangement is such that sudden surges of pressurefrom the wheel cylinders are unimpeded, but pressure surges from thebulb toward the wheel cylinders are dampened by reason of the valve disk256 moving upwardly against a valve seat 266 whereby the liquid mustpass through the restricted orifice 258 in order to move from the bulbtoward the wheel cylinders. Thus the arrangement is such that suddenbounce is not dampened while rebound is dampened, just the reverse ofthe arrangement shown and described in connection with the dampeningvalve 92 of FIGURE 2.

In order to prevent the vehicle level from becoming too low when thevehicle is standing idle at low ambient temperature, a valve 268 isprovided at the juncture between the conduits 242 and 244 and thepassage leading into the bulb 240. The valve 268 is adapted to engage ina valve seat 270 under the influence of a spring (not shown) Wheneverthe vehicle engine is stopped in order to trap the liquid in the wheelcylinders. This substantially reduces the volume of liquid supportingthe vehicle and divorces the wheel cylinders from the substantialcontraction of the polymorphic liquid in the accumulator when thevehicle is standing idle. Thus, while the liquid in the wheel cylindersdoes contract somewhat while the vehicle is standing idle at lowtemperatures, the reduction in volume is relatively small and thevehicle is not lowered drastically. If the valve 268 were not provided,the effect of the added volume in the bulb 240 together with the effectof contraction of the polymorphic liquid 238 would allow the vehicle tobe down on its tires when standing idle.

The valve 268 is controlled by a time delay solenoid 272 which iselectrically connected to the vehicle ignition system (not shown) sothat when the vehicle ignition switch is on, the solenoid 272 isenergized to disengage the valve 268 from the seat 270. The solenoid 272is constructed in any suitable manner to provide a time delay of severalseconds before the valve 268 is opened after the ignition switch isturned on, in order that the polymorphic liquid 238 in the accumulatormay be sufliciently heated before the valve is opened to prevent thevehicle from dropping down due to the initial low volume in theaccumulator.

In connection with the construction of FIGURE 5, the combination ofviscous rebound dampening through the valve 246 and polymorphicspringing through the polymorphic liquid 238 provides an advantageouseffect. As the ambient temperature increases, the stiffening effect ofpolymorphic springing also increases due to less rapid polymorphicchange at elevated temperatures. At the same time when the temperatureis elevated the wheel cylinder liquid becomes thinner and the effect ofviscous dampening through the orifice 258 is reduced. Thus, the efiectof one change substantially balances the effect of the other.

It should here be noted that while the accumulators have been describedas utilizing polymorphic liquids, they can be used with non-polymorphiccompressible liquids. In this event the liquid capacity must beincreased in order to achieve the required volume changes by ordinarycontraction and expansion.

A typical wheel cylinder construction is illustrated in detail in FIGURE6, showing a wheel cylinder generally designated by the referencenumeral 280 which includes a casing 282 and a piston 284. The wheelcylinder 280 is not unlike present day shock absorbers except that it iscompletely filled with a compressible liquid without an expansionchamber. The piston 284 includes a piston rod 286 and a dampening head288 having viscous dampening passages 290 therethrough. A suitableliquid spring seal 292 is provided at the region of entry of the pistonrod into the casing. A passage 294 leads into the casing and isconnected by suitable conduit means such as shown in FIGURE 1 to one ofthe conduits 242 or 244 of the accumulator 230 of FIGURE 5. It will beunderstood that the casing and the piston are connected to therespective sprung and unsprung portions of the vehicle in order toresiliently support the vehicle on the wheels.

The piston 284 of the wheel cylinder 280 is shown in its compressedposition due to insertion of the piston rod 286 into the casing todisplace and compress the compressible liquid therein. The pressure istransmitted through the lines to the bulb 240 of the accumulator so thatpolymorphic transition occurs, or partially occurs, in the polymorphicliquid 238, as represented by the xs shown therein. It is the effect ofthis polymorphic transition which subtracts energy to providepolymorphic rebound dampening as indicated by the curves E and E" ofFIGURE 7. Thus, much of the energy put into the system by compression ofthe piston 284 will not be sent back to the piston in the form ofrebound energy, since a substantial portion of this pressure energy hasbeen converted to heat energy and dissipated in the accumulator aspreviously described.

It will be readily apparent from the foregoing description that thepresent invention provides a very much improved vehicle suspensionsystem which also efiiciently operates as a vehicle leveling system byutilizing waste heat of the engine, or other heating means. With thissystem it is not necessary to provide auxiliary pumps, or the like(which increase bulk and waste horsepower) to provide vehicle leveling.The suspension system of this invention can be utilized to replacepresent springs and shock absorbers or can be used in connection with anexisting spring system. The system is very simple and compact, isinexpensive to build and maintain, and provides greatly improved ridingqualities while at the same time providing improved vehicle leveling.

Variations and modifications may be effected without departing from thescope of the novel concepts of the present invention.

' I claim:

1. A compressible liquid accumulator comprising an insulated container,an inner container disposed in spaced relation in said insulatedcontainer, at flexible container disposed in spaced relation in saidinner container, a compressible liquid in said inner containercompletely filling the space between the inner container and saidflexible container, at compressible force transmitting liquid completelyfilling said flexible container, said force transmitting liquid beingsubjected to pressure surges, a fluid disposed between said insulatedcontainer and said inner container, means for varying the temperature ofsaid compressible liquid in said inner container to change the pressureand volume thereof and to thereby change the pressure and volume of saidforce transmitting liquid, and damper valve means for restricting flowof said force transmitting liquid in one direction relative to saidflexible container to dampen pressure surges of said force transmittingliquid in said one direction.

2. A compressible liquid accumulator comprising an insulated container,an inner container disposed in spaced relation in said insulatedcontainer, a flexible container disposed in spaced relation in saidinner container, a compressible liquid in said inner containercompletely filling the space between the inner container and saidflexible container, a compressible force transmitting liquid completelyfilling said flexible container, a fluid disposed between said insulatedcontainer and said inner container, means for varying the temperature ofsaid fluid to vary the temperature of said compressible liquid in saidinner container to change the pressure and volume thereof and to therebychange the pressure and volume of said compressible force transmittingliquid, valve means for selectively trapping the force transmittingliquid in said flexible container, and time delay mechanism operativelyassociated with said valve means to delay opening of said valve meansfor a predetermined length of time after said time delay mechanism hasbeen energized.

References Cited in the file of this patent UNITED STATES PATENTS386,557 Roberts July 24, 1888 900,511 Fulton Oct. 6, 1908 1,610,189Whittingham Dec. 7, 1926 1,704,141 Mufily Mar. 5, 1929 1,736,984 SheatsNov. 26, 1929 1,977,538 Anderson Oct. 16, 1934 2,037,534 Pymm Apr. 14,1936 2,241,086 Gould May 6, 1941 2,241,620 Shoeld May 13, 1941 2,673,038Vernet et al Mar. 23, 1954 2,879,641 Johnson Mar. 31, 1959 2,895,507Orser July 21, 1959 2,928,233 Kimm Mar. 15, 1960 2,932,322 Mercier Apr.12, 1960 2,949,315 Taylor Aug. 16, 1960 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No" 3, 115,003 December 2%, 1963 PaulH. Taylor It is hereby certified that error appears in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below Column 3 line 33, for "conventionally"read conveniently Signed and sealed this 14th day of July 1964.

(SEAL) Attest: I g

ESTON G. JOHNSON EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A COMPRESSIBLE LIQUID ACCUMULATOR COMPRISING AN INSULATED CONTAINER,AN INNER CONTAINER DISPOSED IN SPACED RELATION IN SAID INSULATEDCONTAINER, A FLEXIBLE CONTAINER DISPOSED IN SPACED RELATION IN SAIDINNER CONTAINER, A COMPRESSIBLE LIQUID IN SAID INNER CONTAINERCOMPLETELY FILLING THE SPACE BETWEEN THE INNER CONTAINER AND SAIDFLEXIBLE CONTAINER, A COMPRESSIBLE FORCE TRANSMITTING LIQUID COMPLETELYFILLING SAID FLEXIBLE CONTAINER, SAID FORCE TRANSMITTING LIQUID BEINGSUBJECTED TO PRESSURE SURGES, A FLUID DISPOSED BETWEEN SAID INSULATEDCONTAINER AND SAID INNER CONTAINER, MEANS FOR VARYING THE TEMPERATURE OFSAID COMPRESSIBLE LIQUID IN SAID INNER CONTAINER TO CHANGE THE PRESSUREAND VOLUME THEREOF AND TO THEREBY CHANGE THE PRESSURE AND VOLUME OF SAIDFORCE TRANSMITTING LIQUID, AND DAMPER VALVE MEANS FOR RESTRICTING FLOWOF SAID FORCE TRANSMITTING LIQUID IN ONE DIRECTION RELATIVE TO SAIDFLEXIBLE CONTAINER TO DAMPEN PRESSURE SURGES OF SAID FORCE TRANSMITTINGLIQUID IN SAID ONE DIRECTION.